1. Field Of The Invention
The present invention relates to the diversion of sheet material, particularly single or variable height stacks of loose sheets of printed paper, from a first path of movement onto a second movement path selectively and without a loss of alignment. More specifically, this invention is directed to apparatus for selectively engaging and guiding printed sheets out of the transport channel of a collating machine, along which such sheets are moving under the influence of pusher dogs, the intercepted sheets being caused to move along a surface that is inclined relative to the direction of motion established by the collating machine transport channel. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Brief Description Of The Prior Art
While not limited thereto in its utility, the present invention is suited for use as a transferring-out facility wherein defective printed sheets or printed-sheet assemblages are removed from the stream of such sheets or sheet assemblages exiting a collating machine or the like. Collating machines, particularly in the book manufacturing industry, are provided with transport channels wherein the printed sheets are engaged by pusher mechanisms, known in the art as dogs, and caused to move in a first direction while being supported against an edge guide. When a defective sheet or stack of sheets is detected, it is necessary to eject such sheet or stack from the stream moving along the collating machine transport channel. U.S. Pat. No. 4,429,795 discloses a transferring-out facility of the type generally described above wherein defective printed-sheet assemblages are captured and ejected while the transport system of the associated collating machine is operating. In the apparatus of U.S. Pat. No. 4,429,795, the transferring-out facility includes a driven conveyor which is angularly oriented with respect to an inclined collating machine transport channel surface. An endless chain runs above the conveyor and supports a plurality of diverting pins which may selectively be caused to move between extended and retracted positions. When a defective printed-sheet assembly is sensed in the collating machine, and a signal commensurate therewith delivered to the transferring-out facility, a pair of these diverting pins are caused to be swung into the extended, i.e., downwardly projecting, position. These downwardly projecting pins pass through an aperture in the transport channel edge guide and intercept the side edge of a printed-sheet assembly which has been propelled by the pusher dogs and is bearing against the edge guide. The transport channel surface is provided with a longitudinal aperture and the diverting pins move within this aperture and thus begin to propel the defective printed-sheet assemblage out of the region in which the pusher dogs are effective and onto the conveyor.
The performance of the transferring-out facility of U.S. Pat. No. 4,429,795 is not entirely satisfactory because the loosely stacked printed sheets, which are resting against the collating machine pressure dogs and the transfer channel edge guide, have a tendency to become misaligned when struck by the diverting pins. This tendency toward misalignment is accentuated while the defective sheets are being conveyed upwardly at an angle and such misalignment occurs principally, but not exclusively, when the apparatus is operated at high repetition rates. Further, such operation at a high repetition rate has a tendency to cause damage to the printed sheets as a result of crushing. If the transferring-out facility of the referenced U.S. Pat. No. 4,429,795 is utilized for diverting very thin printed-sheet assemblages, such assemblages have a tendency to buckle while being guided to an upwardly inclined path defined by a conveyor, the thin printed-sheet assemblage moving in front of a pair of the diverting pins, and such bucking will lead to an interruption in operation.